We conducted a comparative study of ocean heat content (OHC) in the top 2000 m during the Argo-era using 12 latest and representative global ocean datasets. The differences in the global and basins-wide OHC trends were minor among the observation-based datasets, and remarkable among the ocean reanalyzes (RAs). Some RAs might exhibit much higher or lower basins-wide warming rates than the observation-based datasets. In the top 700 m, RAs suggested similar large-scale warming and cooling patterns, in agreement with the observation-based datasets. Below 700 m, the major warming and cooling features were however significantly different between RAs and observation-based datasets. All datasets suffered from relatively larger uncertainties in the highly dynamic regions. Special caution is suggested when estimating the OHC using only a single dataset, especially a RA. Differences of RAs’ OHC from observation-based datasets were significantly reduced when considering their ensemble mean, to be further confirmed with a larger sample of datasets.